Project Abstract The current study aims to characterize fathers' response to infant cry and explore potential predictors, moderators and outcomes of this response. Excessive and inconsolable crying is a common trigger of parental stress, which can compromise parent-child bonding and make the transition to parenthood more challenging. However, when and why fathers' responses to infant cries might trigger parenting stress is unknown. The proposed study seeks to fill this gap by identifying how expectant fathers respond to infant cry across multiple modalities (behavioral, physiological, and neural), and investigating potential predictors and outcomes of these responses. The current study hypothesizes that neural, behavioral and psychophysiological responses to infant cry will predict fathers' parenting stress and father-infant bonding in the first months postpartum. Potential moderators and mediators of fathers' responses to infant cry, such as prenatal testosterone level and childhood exposure to a risky family environment, will be tested. We also plan to test a theoretical model that includes father reactivity to cry sounds as a pathway linking father risk factors to postpartum parenting outcomes. The project will utilize data from the NSF-funded Hormones Across the Transition to Childrearing (HATCH) study, currently being conducted by the Neuroendocrinology of Social Ties (NEST) lab at the University of Southern California (USC). This ongoing study follows pregnant couples from mid-pregnancy into the postpartum period. Data for the proposed study will be collected only from fathers during the prenatal lab visit, an MRI scanning visit scheduled within a few weeks of the main study visit, and a three-month postpartum assessment. Psychophysiological (skin conductance), behavioral (handgrip dynamometer- assessed grip strength modulation), and neural data will be collected from expectant fathers along with salivary testosterone. This approach promises to elucidate how expectant fathers respond to infant cry, and connect these responses to postpartum measures of parenting stress and distressed parental bonding. This project will be a first step in identifying biological risk factors for parenting stress or dysfunctional bonding in the first months postpartum. This project will enable clinicians and researchers to understand the underlying neurobiological processes in response to infant cry that may indicate risk for negative parenting outcomes postpartum.